The present invention relates to a process for producing an object from a shapeable material source, for example a viscous or plastic source and having a chiralic structure, as well as to a device for performing this process.
Throughout the remainder of the description the object formed by drawing or any other process will be called a "fibre", but this term does not constitute a limitation to optical fibres.
The monomodal fibres conventionally produced for telecommunications always have a small quantity of linear birefringence and circular birefringence. As a result these fibres retain neither the linear polarization, nor the circular polarization. The fibre can be given a high level of linear birefringence by breaking the circular symmetry to the benefit of a planar symmetry. It is also possible to consider a reverse method consisting of introducing a high circular birefringence, so as to retain the circular polarization.
One solution for producing this circular polarization consists of subjecting the glass fibre to a static torsional stress, e.g. applied externally by twisting between its two ends. One effect of the twisting of the fibre is to introduce circular birefringence into it.